[systemd-devel] Race condition on systemd-run --scope

[Umut Tezduyar Lindskog]

Hi Lennart,

Were you able to figure out the problem? You were suspecting that we
might not be getting cgroup empty notifications from kernel.

Umut

On Fri, Oct 24, 2014 at 3:19 PM, Umut Tezduyar Lindskog
<umut at tezduyar.com> wrote:
> Hi,
>
> Since you said you have covered my theories when you implemented, I
> have stopped looking in to this.
>
> Following:
>
> [root at axis-00408cc563e5 /mnt/flash/root]27929# cat stress
> #!/bin/sh
>
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> systemd-run --scope /bin/true &
> [root at axis-00408cc563e5 /mnt/flash/root]27929# ./stress
> [root at axis-00408cc563e5 /mnt/flash/root]27929# Running as unit run-27947.scope.
> Running as unit run-27946.scope.
> Running as unit run-27945.scope.
> Running as unit run-27948.scope.
> Running as unit run-27952.scope.
> Running as unit run-27950.scope.
> Running as unit run-27951.scope.
> Running as unit run-27949.scope.
>
> [root at axis-00408cc563e5 /mnt/flash/root]27929# systemctl -t scope
> UNIT            LOAD   ACTIVE SUB     DESCRIPTION
> run-27945.scope loaded active running /bin/true
> run-27946.scope loaded active running /bin/true
> run-27947.scope loaded active running /bin/true
> run-27948.scope loaded active running /bin/true
> run-27949.scope loaded active running /bin/true
> run-27950.scope loaded active running /bin/true
> run-27951.scope loaded active running /bin/true
> run-27952.scope loaded active running /bin/true
>
> LOAD   = Reflects whether the unit definition was properly loaded.
> ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
> SUB    = The low-level unit activation state, values depend on unit type.
>
> 8 loaded units listed. Pass --all to see loaded but inactive units, too.
> To show all installed unit files use 'systemctl list-unit-files'.
> [root at axis-00408cc563e5 /mnt/flash/root]27929# systemctl status run-27945.scope
> ● run-27945.scope - /bin/true
>    Loaded: loaded (/run/systemd/system/run-27945.scope; static)
>   Drop-In: /run/systemd/system/run-27945.scope.d
>            └─50-Description.conf
>    Active: active (running) since Fri 2014-10-24 13:13:26 GMT; 15s ago
>
> On Fri, Oct 24, 2014 at 1:40 AM, Lennart Poettering
> <lennart at poettering.net> wrote:
>> On Mon, 29.09.14 15:34, Umut Tezduyar Lindskog (umut at tezduyar.com) wrote:
>>
>>> Hi,
>>>
>>> I have stumbled on a race condition on systemd-run --scope command.
>>> Due to race condition, unit might show up as active/running even
>>> though there is no process in the cgroup.
>>
>> Umut!
>>
>> At the hackfest in Düsseldorf you showed me an easy way how to
>> reproduce this issue, what was that again?
>>
>> Lennart
>>
>> --
>> Lennart Poettering, Red Hat